1. Field of the Invention
The present invention relates to optical switches and particularly to MEMS switches.
2. Technical Background
Telecommunication systems utilizing optical waveguides require the use of optical switches for selectively coupling signal sources to one or more destinations. In planar optical components, MEMS switches have included a micro mirror positioned in a diagonal slot formed at the intersection of crossing planar waveguides having ports facing the slot. The micro mirror is moved laterally to reflect incoming light from one waveguide to an adjacent waveguide communicating with the slot to perform a switching function. Such devices for a 16xc3x9716 input/output switch module requires an array of 256 MEMS switches. Although prior MEMS devices provide adequate switching functions, they are difficult to manufacture and their construction does not allow the formation of electrical circuits on the switch module for coupling electro-optical components to the combined MEMS and optical component.
There exists a need, therefore, for an improved MEMS optical switch and an optical switch module including MEMS switches in which an array of MEMS switches are joined with a planar optical circuit and which is capable of receiving electrical circuits for coupling electro-optical devices to the planar optical circuit. There also exists a need for a process for forming multiple switch arrays and multiple planar optical circuit arrays which can be coupled for the mass production of optical switch modules.
The optical switch of the present invention satisfies this need by forming arrays of MEMS switches on a wafer substrate with each switch integrally including a cantilevered arm having a control element at one end for moving into a waveguide slot of planar optical circuit arrays to which the MEMS arrays are mounted. The control element moves in a direction orthogonal to the junction of the MEMS arrays and the optical circuit arrays and, in a preferred embodiment, comprises a mirror. The cantilevered arm can be actuated by thermal, piezoelectric, or electrostatic means to deflect the arm between rest and actuated positions. In the rest position, signal information from a waveguide port passes across the slot into a second waveguide port. When the switch is actuated, the mirrored end of the cantilevered arm extends into the slot for selectively blocking or changing the direction of the incoming signal directing the signal to the port of a different waveguide.
In an alternative embodiment of the invention, a second cantilevered arm is provided which moves in a plane orthogonally to the first cantilevered arm and is selectively actuated in sequence with the first cantilevered arm for overlying and latching the first or switching arm in an actuated position, such that the MEMS switch can remain in an active state without further application of a control signal thereto. In all embodiments, the optical switch module so formed allows the formation of electrical conductors on a surface for the coupling of electro-optical components to the planar optical circuit, as well as for the actuation of the MEMS switches. This invention also includes a method of simultaneously fabricating multiple optical switch modules utilizing masking, etching, depositing, and bonding steps to form such multiple optical switch modules, each with multiple arrays of fiber optical waveguides and arrays of MEMS switches as well as providing electrical circuits thereon.
Additional features and advantages of the invention will be set forth in the detailed description which follows and will be apparent to those skilled in the art from the description or recognized by practicing the invention as described in the description which follows together with the claims and appended drawings.
It is to be understood that the foregoing description is exemplary of the invention only and is intended to provide an overview for the understanding of the nature and character of the invention as it is defined by the claims. The accompanying drawings are included to provide a further understanding of the invention and are incorporated and constitute part of this specification. The drawings illustrate various features and embodiments of the invention which, together with their description serve to explain the principals and operation of the invention.